Engine flywheel torque determination method/system

ABSTRACT

An adaptive control system/method for an at least partially automated vehicular mechanical transmission system (10) is provided for determining the current value of a control parameter (T FW ) indicative of engine flywheel torque. Engine flywheel torque (T FW ) is determined as a function of the expression gross engine torque (T EG ) is equal to the sum of flywheel torque (T FW ), base engine friction torque (T BEF ), acceleration torque (T ACCEL ) and accessory torque (T ACCES ). Accessory torque (T ACCES ) is determined, when the vehicle is in motion, as a function of engine deceleration rate (dES/dt rate). Flywheel torque (T FW ), or drivewheel torque (T DW ) determined as a function of flywheel torque (T FW ) and drivetrain parameters such as engaged gear ratio (GR), is utilized as a control parameter for controlling shifting of the transmission system.

RELATED APPLICATIONS

This application is related to U.S. Ser. No. 08/179,060, entitled ENGINEBRAKE ENHANCED UPSHIFT CONTROL METHOD/SYSTEM, filed Jan. 7, 1994, nowU.S. Pat. No. 5,425,689, and assigned to the same assignee, EATONCORPORATION, as is this application.

This application is related to U.S. Ser. No. 08/192,522, entitledMETHOD/SYSTEM TO DETERMINE GROSS COMBINATION WEIGHT OF VEHICLES, filedFeb. 7, 1994, now U.S. Pat. No. 5,490,063, and assigned to the sameassignee, EATON CORPORATION, as is this application.

This application is related to U.S. Ser. No. 08/227,749, entitledADAPTIVE SHIFT CONTROL METHOD/SYSTEM, filed Apr. 12, 1994, now allowed,and assigned to the same assignee, EATON CORPORATION, as is thisapplication.

This application is related to U.S. Ser. No. 08/225,271, entitled ENGINEDECELERATION DETERMINATION METHOD/SYSTEM, filed Apr. 5, 1994, nowallowed, and assigned to the same assignee, EATON CORPORATION, as isthis application.

This application is related to U.S. Ser. No. 08/242,824, entitled ENGINEACCESSORY TORQUE AND ENGINE DECELERATION RATE DETERMINATIONMETHOD/SYSTEM, filed the same day, May 16, 1994, still pending andassigned to the same assignee, EATON CORPORATION, as is thisapplication.

BACKGROUND OF THE INVENTION

1. Field of Invention

This invention relates to shift control methods/systems for at leastpartially automated vehicular mechanical transmission systems includingvarious shift control techniques, such as control techniques wherein thedesirability and/or probability of successfully completing a selectedupshift are evaluated in view of existing vehicle operating conditions,which are based, at least in part, on determining and/or predicting thedriving torque available at the vehicle drivewheels. In particular, thepresent invention relates to an adaptive shift control method/system fora fully or partially automated vehicular mechanical transmission systemof the type shifting without disengagement of the vehicular masterclutch which will determine a value indicative of vehicle drivewheeltorque and will use this value as a transmission system controlparameter.

More particularly, the present invention relates to an adaptive shiftcontrol for vehicular automated mechanical transmission systems whichwill continuously update the value of the control parameter indicativeof engine flywheel torque, from which value and certain drivetraincharacteristics, such as engaged gear ratio, tire size, efficiency,etc., drivewheel torque may be accurately determined. For automated orpartially automated mechanical transmission systems, it is desirable toknow the torque at the flywheel for many control algorithms. Knowingtrue torque at the flywheel will allow more precise shift control andmakes possible advanced algorithms, such as shiftability and GCWcalculations. The control system/method of the present invention usestorque information from the engine (preferably an electronic engine),along with vehicle and engine acceleration information, to determinethis parameter.

2. Description of the Prior Art

Fully automatic and semi-automatic vehicular mechanical transmissionsystems utilizing electronic control units, usuallymicroprocessor-based, are known in the prior art. Examples of suchautomated mechanical transmission systems may be seen by reference toU.S. Pat. Nos. 3,961,546; 4,361,060; 4,425,620; 4,631,679 and 4,648,290,the disclosures of which are incorporated herein by reference.

Another type of partially automated vehicular transmission systemutilizes an automatic or semi-automatic shift implementationsystem/method for a mechanical transmission system for use in vehicleshaving a manually only controlled master clutch. The system usually hasat least one mode of operation wherein the shifts to be automatically orsemi-automatically implemented are automatically preselected. Anelectronic control unit (ECU) is provided for receiving input signalsindicative of transmission input and output shaft speeds and/or enginespeed and for processing same in accordance with predetermined logicrules to determine (i) if synchronous conditions exist, and (ii) in theautomatic preselection mode, if an upshift or downshift from thecurrently engaged ratio is required and to issue command output signalsto a transmission actuator and/or an engine fuel controller for shiftingthe transmission in accordance with the command output signals.

Transmission systems of this general type may be seen by reference toU.S. Pat. Nos. 5,050,079; 5,053,959; 5,053,961; 5,053,962; 5,063,511;5,081,588; 5,089,962; 5,089,965 and 5,272,939, the disclosures of whichare incorporated herein by reference.

While the above-described automatic and/or partially automatic shiftimplementation type vehicular mechanical transmission systems are wellsuited for their intended applications, they are not totallysatisfactory as they will occasionally initiate an attempted shift,which, due to vehicle operating conditions, should not be permittedand/or cannot be completed. This is especially a concern for upshifts ofa vehicle heavily loaded and/or traveling up a grade and/or for thoseautomated mechanical transmission systems not provided with an automatedclutch actuator and/or an input shaft brake and thus have input shaftdeceleration limited to the normal or engine brake-assisted decay rateof the engine.

In accordance with the inventions of aforementioned co-pending U.S. Ser.No. 08/179,060 and U.S. Pat. No. 5,272,939, and of U.S. Pat. Nos.5,133,229; 5,172,609 and 5,231,582, the disclosures of which areincorporated herein by reference, the above-discussed drawbacks of theprior art are minimized or overcome by the provision of shift controlmethods/systems for vehicular at least partially automated mechanicaltransmission systems which, upon sensing an automatic or manualselection of an upshift from a currently engaged gear ratio into atarget gear ratio will, based upon currently sensed vehicle operatingconditions, determine if the selected upshift is feasible (i.e.,desirable and/or probably completible) and only initiate feasibleshifts.

If the proposed upshift is not feasible, the shift request may bemodified (i.e., a skip shift request changed to single shift) orcancelled for a predetermined period of time (such as 10 seconds).

The foregoing prior art control logic was not totally satisfactory, asthe control parameter value indicative of drivewheel torque requiredexpensive shaft torque sensors to acquire and/or was derived from grossengine torque values which do not account for torque losses due tovehicle assembler-installed accessories (such as air-conditioning,alternator, etc.) and for accelerating the engine, For example, duringacceleration in the low gears of a heavy truck, the torque numberreported from the engine on an SAE J1939-type datalink is a fairly highnumber at wide-open throttle. However, most of the torque the engine"says" it is producing is going to accelerate the engine rotatinginertia and only a portion of that reported torque is going from theflywheel through the clutch to actually move the vehicle.

SUMMARY OF THE INVENTION

In accordance with the present invention, the drawbacks of the prior artare minimized or overcome by the provision of an adaptive control for anat least partially automated vehicular mechanical transmission systemwhich accurately determines a value indicative of engine flywheel torqueunder current vehicle operating conditions. The control is particularlyuseful for vehicular automated mechanical transmission systemscommunicating with an electronically controlled internal combustionengine by means of a datalink of the type conforming to a protocolsimilar to SAE J1922 or J1939.

In a preferred embodiment of the present invention, the above isaccomplished in a vehicular automated mechanical transmission systemcontrol of the type not automatically disengaging the master clutchduring shifting operations, by utilizing the relationship that:

    T.sub.EG =T.sub.FW +T.sub.BEF +T.sub.ACCES +T.sub.ACCEL

where:

T_(EG) =gross engine torque;

T_(FW) =engine flywheel torque;

T_(BEF) =base engine friction torque (includes the torque to overcomeengine internal friction and the torque to rotate the enginemanufacturer-installed accessories (i.e., water pump, oil pump, etc.));

T_(ACCES) =accessory torque (torque to operate vehicle accessories, suchas air-conditioning, fans, lights, etc.); and

T_(ACCEL) =torque to accelerate engine, calculated from engineacceleration or deceleration and moment of inertia (I) of engine.

Instantaneous values representative of gross engine torque (T_(EG)) andbase engine friction torque (T_(BEF)) are available on the datalink.T_(ACCEL) is determined from sensed engine acceleration (which may benegative) and a calibrated moment of inertia (I) of the engine.Accessory torque (T_(ACCES)) is a constantly determined value which,Applicant has determined, may be taken as net engine torque (i.e.,T_(EG) -T_(BEF)) if the vehicle is idling with the transmission inneutral and is related to engine deceleration rate in a known,substantially linear manner when the vehicle is in motion.

Accordingly, an adaptive control system/method for an at least partiallyautomated vehicular mechanical transmission system is provided whichcontinuously updates the value of a control parameter (T_(FW))indicative of flywheel torque.

This and other objects and advantages of the present invention willbecome apparent from a reading of the detailed description of thepreferred embodiment taken in connection with the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of the vehicular mechanicaltransmission system partially automated by the system of the presentinvention.

FIG. 1A is a schematic illustration of the shift pattern of thetransmission of FIG. 1.

FIG. 2 is a schematic illustration of the automatic preselect andsemi-automatic shift implementation system for a mechanical transmissionsystem of the present invention.

FIG. 3A is a schematic illustration of logic for differentiating signalsrepresentative of current vehicle and engine speed.

FIG. 3B is a schematic illustration of logic for calculating an expectedvehicle acceleration during the shift transient when zero engine torqueis applied to the drive wheels.

FIGS. 4A and 4B are schematic illustrations, in flow chart format, ofthe inventive control method of the present invention.

FIG. 5 is a graphical representation of an upshift event illustratingboth feasible and not feasible attempted shifts.

FIG. 6 is a graphical representation, similar to FIG. 5, of engine speedand input shaft speed during an upshift.

FIG. 7 is a graphical representation of the substantially linearrelationship between accessory torque (T_(ACCES)) and enginedeceleration rate (dES/dt rate).

DESCRIPTION OF THE PREFERRED EMBODIMENT

Certain terminology will be used in the following description forconvenience in reference only and will not be limiting. The words"upwardly", "downwardly", "rightwardly", and "leftwardly" will designatedirections in the drawings to which reference is made. The words"forward", "rearward", will refer respectively to the front and rearends of the transmission as conventionally mounted in a vehicle, beingrespectfully from left and right sides of the transmission asillustrated in FIG. 1. The words "inwardly" and "outwardly" will referto directions toward and away from, respectively, the geometric centerof the device and designated parts thereof. Said terminology willinclude the words above specifically mentioned, derivatives thereof andwords of similar import.

The term "compound transmission" is used to designate a change speed orchange gear transmission having a multiple forward speed maintransmission section and a multiple speed auxiliary transmission sectionconnected in series whereby the selected gear reduction in the maintransmission section may be compounded by further selected gearreduction in the auxiliary transmission section. "Synchronized clutchassembly" and words of similar import shall designate a clutch assemblyutilized to nonrotatably couple a selected gear to a shaft by means of apositive clutch in which attempted engagement of said clutch isprevented until the members of the clutch are at substantiallysynchronous rotation. A relatively large capacity friction means areutilized with the clutch members and are sufficient, upon initiation ofa clutch engagement, to cause the clutch members and all membersrotating therewith to rotate at substantially synchronous speed.

The term "upshift" as used herein, shall mean the shifting from a lowerspeed gear ratio into a higher speed gear ratio. The term "downshift" asused herein, shall mean the shifting from a higher speed gear ratio to alower speed gear ratio. The terms "low speed gear", "low gear" and/or"first gear" as used herein, shall all designate the gear ratio utilizedfor lowest forward speed operation in a transmission or transmissionsection, i.e., that set of gears having the highest ratio of reductionrelative to the input shaft of the transmission.

Referring to FIG. 1, a range-type compound transmission 10 of the typeat least partially automated by a semi-automatic mechanical transmissionsystem having an automatic preselect mode of operation is illustrated.Compound transmission 10 comprises a multiple speed main transmissionsection 12 connected in series with a range type auxiliary section 14.Transmission 10 is housed within a housing H and includes an input shaft16 driven by a prime mover such as diesel engine E through a selectivelydisengaged, normally engaged friction master clutch C having an input ordriving portion 18 drivingly connected to the engine crankshaft 20 and adriven portion 22 rotatably fixed to the transmission input shaft 16.

The engine E is fuel throttle controlled, preferably electronically, andis connected to an electronic datalink DL of the type defined in SAE J1922 or J 1939 protocol, and the master clutch C is manually controlledby a clutch pedal (not shown) or the like. Typically, the clutch C isutilized only for start-from-stop and for inching operation of thevehicle.

Transmissions similar to mechanical transmission 10 are well known inthe prior art and may be appreciated by reference to U.S. Pat. Nos.3,105,395; 3,283,613 and 4,754,665, the disclosures of which areincorporated by reference.

Partially automated vehicular mechanical transmission systems of thetype illustrated may be seen by reference to above-mentioned U.S. Pat.Nos. 5,050,079; 5,053,959; 5,053,961; 5,053,962; 5,063,511; 5,089,965and 5,272,939.

Although the control method/system of the present invention isparticularly useful for those automated mechanical transmission systemsnot having automatic clutch actuators or input shaft brakes, the presentinvention is not limited to such use.

In main transmission section 12, the input shaft 16 carries an inputgear 24 for simultaneously driving a plurality of substantiallyidentical countershaft assemblies 26 and 26A at substantially identicalrotational speeds. The two substantially identical countershaftassemblies are provided on diametrically opposite sides of mainshaft 28which is generally coaxially aligned with the input shaft 16. Each ofthe countershaft assemblies comprises a countershaft 30 supported bybearings 32 and 34 in housing H, only a portion of which isschematically illustrated. Each of the countershafts is provided with anidentical grouping of countershaft gears 38, 40, 42, 44, 46 and 48,fixed for rotation therewith. A plurality of mainshaft gears 50, 52, 54,56 and 58 surround the mainshaft 28 and are selectively clutchable, oneat a time, to the mainshaft 28 for rotation therewith by sliding clutchcollars 60, 62 and 64 as is well known in the prior art. Clutch collar60 may also be utilized to clutch input gear 24 to mainshaft 28 toprovide a direct drive relationship between input shaft 16 and mainshaft28.

Typically, clutch collars 60, 62 and 64 are axially positioned by meansof shift forks associated with the shift housing assembly 70, as wellknown in the prior art. Clutch collars 60, 62 and 64 may be of the wellknown nonsynchronized double acting jaw clutch type.

Shift housing or actuator 70 is actuated by compressed fluid, such ascompressed air, and is of the type automatically controllable by acontrol unit as may be seen by reference to U.S. Pat. Nos. 4,445,393;4,555,959; 4,361,060; 4,722,237; 4,873,881; 4,928,544 and 2,931,237, thedisclosures of which are incorporated by reference.

Mainshaft gear 58 is the reverse gear and is in continuous meshingengagement with countershaft gears 48 by means of conventionalintermediate idler gears (not shown). It should also be noted that whilemain transmission section 12 does provide five selectable forward speedratios, the lowest forward speed ratio, namely that provided bydrivingly connecting mainshaft drive gear 56 to mainshaft 28, is oftenof such a high gear reduction it has to be considered a low or "creeper"gear which is utilized only for starting of a vehicle under severeconditions and, is not usually utilized in the high transmission range.Accordingly, while main transmission section 12 does provide fiveforward speeds, it is usually referred to as a "four plus one" mainsection as only four of the forward speeds are compounded by theauxiliary range transmission section 14 utilized therewith.

Jaw clutches 60, 62, and 64 are three-position clutches in that they maybe positioned in the centered, nonengaged position as illustrated, or ina fully rightwardly engaged or fully leftwardly engaged position bymeans of actuator 70. As is well known, only one of the clutches 60, 62and 64 is engageable at a given time and main section interlock means(not shown) are provided to lock the other clutches in the neutralcondition.

Auxiliary transmission range section 14 includes two substantiallyidentical auxiliary countershaft assemblies 74 and 74A, each comprisingan auxiliary countershaft 76 supported by bearings 78 and 80 in housingH and carrying two auxiliary section countershaft gears 82 and 84 forrotation therewith. Auxiliary countershaft gears 82 are constantlymeshed with and support range/output gear 86 while auxiliary sectioncountershaft gears 84 are constantly meshed with output gear 88.

A two-position synchronized jaw clutch assembly 92, which is axiallypositioned by means of a shift fork (not shown) and the range sectionshifting actuator assembly 96, is provided for clutching either gear 86to output shaft 90 for direct or high range operation or gear 88 tooutput shaft 90 for low range operation of the compound transmission 10.The "shift pattern" for compound range type transmission 10 isschematically illustrated in FIG. 1A.

Range section actuator 96 may be of the type illustrated in U.S. Pat.Nos. 3,648,546; 4,440,037 and 4,614,126, the disclosures of which areincorporated herein by reference.

Although the range-type auxiliary section 14 is illustrated as atwo-speed section utilizing spur or helical type gearing, it isunderstood that the present invention is also applicable to range typetransmissions utilizing combined splitter/range type auxiliary sections,having three or more selectable range ratios and/or utilizing planetarytype gearing. Also, any one or more of clutches 60, 62 or 64 may be ofthe synchronized jaw clutch type and transmission sections 12 and/or 14may be of the single countershaft type.

For purposes of providing the automatic preselect mode of operation andthe automatic or semi-automatic shift implementation operation oftransmission 10, an input shaft speed (IS) sensor and an output shaftspeed (OS) sensor 100 are utilized. Alternatively to output shaft speedsensor 100, a sensor 102 for sensing the rotational speed of auxiliarysection countershaft gear 82 may be utilized. The rotational speed ofgear 82 is, of course, a known function of the rotational speed ofmainshaft 28 and, if clutch 92 is engaged in a known position, afunction of the rotational speed of output shaft 90. Further, with mainclutch C fully engaged, input shaft speed (IS) will equal engine speed(ES).

The automatic preselect and automatic or semi-automatic shiftimplementation control system 104 for a mechanical transmission systemof the present invention is schematically illustrated in FIG. 2. Controlsystem 104, in addition to the mechanical transmission 10 describedabove, includes an electronic control unit 106, preferablymicroprocessor based, for receiving input signals from the input shaftspeed sensor 98, from the output shaft speed sensor 100 (or,alternatively, the mainshaft speed sensor 102), from the driver controlconsole 108, from a throttle pedal P position sensor 152, and from theengine E though datalink DL. Typically, at least information indicativeof engine speed (ES), gross engine torque (T_(EG)) and base enginefriction torque (T_(BEF)) will be available on the datalink. The ECU 106may also receive inputs from an auxiliary section position sensor 110.

The ECU 106 may be of the type schematically illustrated in U.S. Pat.No. 4,595,986, the disclosure of which is incorporated herein byreference. The ECU is effective to process the inputs in accordance withpredetermined logic rules to issue command output signals to atransmission operator, such as solenoid manifold 112 which controls themainsection section actuator 70 and the auxiliary section actuator 96,and to the driver control console 108, and through the datalink DL toengine E.

In the preferred embodiment, the driver control counsel allows theoperator to manually select a shift in a given direction (up or down) orto neutral from the currently engaged ratio, or to select asemi-automatic preselect mode of operation (D), and preferably providesa display for informing the operator of the current mode of operation(automatic or manual preselection of shifting), the current transmissionoperation condition (forward, reverse or neutral) and of any ratiochange or shift (upshift, downshift or shift to neutral) which has beenpreselected but not yet implemented.

Console 108 may be of the "R-N-D-H-L" (i.e.,reverse-neutral-drive-hold-low) type with a manual upshift and downshiftselector.

To implement a selected shift, the manifold 112 is preselected to causeactuator 70 to be biased to shift main transmission section 12 intoneutral. This is accomplished by the operator or the ECU controllercausing a torque reversal by momentarily decreasing and/or increasingthe supply of fuel to the engine, see U.S. Pat. No. 4,850,236, thedisclosure of which is incorporated herein by reference. As thetransmission is shifted into neutral, and neutral is verified by the ECU(neutral sensed for a period of time such as 1.5 seconds), if theselected shift is a compound shift, i.e., a shift of both the mainsection 12 and of the range section 14, such as a shift from fourth tofifth speeds as seen in FIG. 1A, the ECU will issue command outputsignals to manifold 112 to cause the auxiliary section actuator 96 tocomplete the range shift after neutral is sensed in the front box.

When the range auxiliary section is engaged in the proper ratio, the ECUwill calculate or otherwise determine, and continue to update, anenabling range or band of input shaft speeds, based upon sensed outputshaft (vehicle) speed and the ratio to be engaged (GR_(TARGET)), whichwill result in an acceptably synchronous engagement of the ratio to beengaged. As the operator or the ECU, by throttle manipulation, causesthe input shaft speed to fall within the acceptable range, the ECU 106will issue command output signals to manifold 112 to cause actuator 70to engage the mainsection ratio to be engaged.

Under certain operating conditions of the vehicle, an automatically ormanually selected shift may not be completable or will result inunacceptable vehicle performance after completion of an upshift. Theseconditions usually involve upshifts when the vehicle is heavy loadedand/or is traveling against a great resistance, such as in mud, up asteep grade and/or into a strong headwind.

By way of example, to achieve substantial synchronous conditions tocomplete an upshift, the speed of the input shaft 10 (whichsubstantially equals the speed of the engine E with the master clutchengaged) must be decreased to substantially equal the speed of theoutput shaft 90 (directly proportional to vehicle speed) multiplied bythe target gear ratio. As an automated clutch actuator and input shaftbrake are not provided, the speed of the input shaft will decrease withthe rate of decay of engine speed. Thus, to achieve substantiallysynchronous conditions for engagement of the target ratio, IS shouldsubstantially equal OS*GR_(TARGET) and, with the master clutch fullyengaged, IS will substantially equal ES.

The sequence of an upshift of the illustrated automated mechanicaltransmission system is graphically illustrated in FIG. 5. Line 200represents the input shaft speed (IS) at vehicle conditions prior to theupshift point 202 wherein the current gear ratio (GR) is fully engaged,the master clutch C is fully engaged, and ES=IS=OS*GR. Upon a shift intoneutral, as the engine is defueled (i.e., fueling of the engine isreduced to a minimum value), the input shaft speed and engine speed willdecay at the constant (but not necessarily linear) rate (dIS/dt)represented by line 204 until idle speed 206 is reached. The expectedspeed of the output shaft 90 during the shift transient when zero enginetorque is applied to the vehicle drive wheels (OS_(EXPECTED)) multipliedby the target gear ratio, which product is the required synchronousspeed of the input shaft/engine, is represented by lines 208 and 210illustrating, respectively, that product at a lesser or greaterresistance to motion of the vehicle. As may be seen, under conditions oflower resistance (line 208), synchronous will occur at point 212 and theselected upshift is feasible while, under conditions of greaterresistance (line 210), substantial synchronous will not occur and theselected upshift is not feasible.

In a typical diesel engine of a heavy duty truck, the engine/input shaftdecay rate is about 300 to 800 RPM and both the engine and vehicledeceleration may be approximated as linear. The specific rate of decayof the engine and/or input shaft may be learned by differentiating thevalue of ES and/or IS signals during a defueling condition (see, forexample, aforementioned U.S. Pat. No. 4,361,060). The decay rate mayvary considerably, however, with temperature and use of engine-drivenaccessories.

As may be seen by reference to FIG. 5, if the input shaft speed (IS) (asdetermined by initial input shaft speed at point 202 and theacceleration of the input shaft (dIS/dt)) will be substantially equal tothe product of expected output shaft speed at zero torque to the vehicledrive wheels (OS_(EXPECTED)), which is determined by initial OS (-IS/GR)and the vehicle acceleration (dOS/dt) at current resistance to vehiclemotion, multiplied by the numerical value of the target gear ratio(GR_(TARGET)) at a value greater than a reference (such as engine idlespeed 206), then achieving a synchronous shift into the selected targetgear ratio is feasible; if not, achieving a substantially synchronousshift into the selected target gear ratio is infeasible. The OS anddOS/dt signals are, of course, equivalent to vehicle speed and vehicleacceleration signals, respectively. The reference value is illustratedas engine idle speed 206 but can be a lower positive value if the masterclutch is manually or automatically disengaged.

For purposes of feasibility determination, for vehicles having a widelyvariable gross combined weight ("GCW"), i.e., combined weight ofvehicle, fuel, cargo (if any) passengers (if any) and operator, thecontroller will determine current GCW. From this information, the systemcan determine what the vehicle acceleration (usually a deceleration)will be at zero driveline torque, i.e., the slope of line 208 or 210.Based upon this information and a present or learned value of enginedecay rate, i.e., the slope of line 204, which may vary with enginespeed, operating temperature, operation of an engine brake, etc., theECU can then determine if, under current vehicle operating conditions,the system is able to successfully complete the proposed upshift. Basedupon this information, the control system can then either (i) issuecommand signals to implement the proposed upshift, or (ii) modify theproposed shift (usually command a single rather than a skip upshift, or(iii) cancel/prohibit the shift request for a predetermined period oftime (such as, for example, about 10 seconds).

Briefly, the acceleration of the vehicle at zero torque to the drivewheels can be approximated by the relationship:

    A.sub.O TORQUE =A.sub.i -(T.sub.i /CW)

where:

A_(i) =vehicle acceleration at engine torque i to the drive wheels,

C=a constant,

T_(i) =engine torque i to the drive wheels, and

W=gross combined vehicle weight.

FIG. 3A schematically illustrates a logic element or subroutine 220 fordifferentiating various input signals 222, such as OS and/or ES, todetermine the derivatives with respect to time thereof, dOS/dt and/ordES/dt, as output signals 224.

FIG. 3B schematically illustrates a logic element or subroutine 226wherein input signals 228, including signals indicative of engine torqueand vehicle acceleration (dOS/dt), are processed according to the logicrules set forth above to determine an output signal value 230 indicativeof expected vehicle acceleration (dOS/dt) during the shift transientwhen no engine torque is applied to the vehicle drive wheels.

The foregoing is illustrative of a control system which automaticallyevaluates the feasibility, under current vehicle operating conditions,of manually or automatically preselected shifts and either causes suchproposed shifts to be executed, modified or cancelled. In the event of amanually selected upshift determined to be unfeasible, the operator maybe issued a tactile, audible or visual warning.

As illustrated above, in fully automated or partially automatedmechanical transmission systems, it is desirable to know the torque atthe flywheel for many control algorithms. Knowing true torque at theflywheel will allow more precise shift control and makes possibleadvanced algorithms, such as shiftability and GCW calculations. Thecontrol of this invention uses torque information from the engine(preferably an electronic engine) along with vehicle and engineacceleration information to calculate this control parameter.

For controlling a fully or partially automated vehicular mechanicaltransmission system, it is important to be able to determine an accuratevalue indicative of drivewheel torque. Drivewheel torque may bedetermined as a function of engine flywheel torque (i.e., input torqueto the vehicle master clutch or torque converter) if drivetrainparameters, such as current transmission gear ratio, drive axle ratio,drivetrain efficiency and tire size, are known.

For heavy-duty vehicles with electronically controlled enginescommunicating on datalinks of the type defined in SAE J1922 and J1939protocols, engine torque may be represented by the relationship:

    T.sub.EG =T.sub.FW +T.sub.BEF +T.sub.ACCES +T.sub.ACCEL

where:

T_(EG) =gross engine torque;

T_(FW) =flywheel torque;

T_(BEF) =base engine friction torque;

T_(ACCES) =accessory torque; and

T_(ACCEL) =torque to accelerate the engine.

Gross engine torque (T_(EG)) and base engine friction torque (T_(BEF)),the torque necessary to drive engine manufacturer-supplied devices (suchas oil pumps) and to overcome internal engine friction, are parametersavailable on the electronic databus (DL). Torque to accelerate theengine (T_(ACCEL)) is determined as a function of sensed engineacceleration and known engine moment of inertia (T_(ACCEL) =dES/dt *I_(ENGINE)). It is noted that T_(ACCEL) may have a positive or negativevalue.

Accordingly, to determine flywheel torque (T_(FW)), which is a controlparameter in shiftability logic, GCW determination logic and the like,it is necessary to provide a control technique for determining accessorytorque (T_(ACCES)). The value of accessory torque (T_(ACCES)) may varysubstantially and often, as vehicular accessories such as lights,air-conditioning, fan drives and the like are turned off and onautomatically or by the vehicle operator and/or passengers.

Assuming unaided engine deceleration during defueling of the engine (noengine brake operation), it has been observed that engine accessorytorque (T_(ACCES)) and engine deceleration rate (dES/dt rate) varydependently upon each other. Engine deceleration rate (dES/dt rate) isthe rate of engine deceleration when the transmission is in neutraland/or the master clutch is fully disengaged, and engine fueling is at aminimal value. As accessory load increases, the engine deceleration rateincreases in proportion to it.

For controlling the automated mechanical transmission system, it alsomay be necessary to determine the engine deceleration rate (dES/dt) at atime when the vehicle is not in motion and/or has not been shifting.

Engine deceleration when the vehicle is in motion and upshifting isdetermined as follows. For automated transmission systems of the typehaving an engine controlled by the ECU over an electronic datalink ofthe type defined in the SAE J1922 or J1939 protocol, the engine isoperated in a "predip" mode prior to disengagement of the existingratio, in a "synchronizing" mode after a shift from the existing ratiointo neutral, and in the "throttle recovery" mode immediately afterengagement of the target gear ratio. The engine and input shaft speedsin these modes are illustrated in FIG. 6. In the "predip" mode, fuelingis modulated to cause driveline torque reversals to relieve torque lockconditions. In the "synchronizing" mode, engine fueling is minimized,allowing engine and input shaft speeds to decay down to a synchronousspeed for engaging the target gear ratio (ES=IS=OS * GR_(TARGET)). Inthe "throttle recovery" mode, the fueling of the engine is smoothlyreturned to that value indicated by the operator's positioning of thethrottle pedal.

To accurately determine the current engine deceleration rate value whilein the synchronous mode of engine operation, and to minimize the effectsof noise, torsionals and the like, it is important that for eachmeasurement, the greatest possible differential between initial andfinal engine speed be utilized, and that a filtering technique beutilized. Accordingly, to determine a value indicative of current enginedeceleration, readings must be taken during the synchronous enginecontrol phase of an upshift, and should include a first reading at ornear point A in FIG. 6 when the synchronous engine control phase isfirst initiated, and a second reading at or near point B in FIG. 6 whenthe synchronous engine control phase is ended or is about to end. Thecurrent value for engine deceleration (dES_(CURRENT)) will then be(RPM_(A) -RPM_(B))÷(Time_(A) -Time_(B)). This value is then filtered toprovide an updated control parameter, for example:

    dES.sub.UPDATED = (dES.sub.CURRENT)+((7) * (dES.sub.PREVIOUS))!÷8

The occurrence of point A is taken as the first time operation in thesynchronous mode is sensed. The occurrence of point B is taken as thefirst time operation in the throttle recovery mode is sensed. As nomeasurable change in engine speed is expected in the cycle times betweenentering the upshift engine control subroutine (i.e., about 40milliseconds), this is a very accurate method of obtaining the maximummagnitude of change in engine speed during the synchronous operation ofeach upshift.

Experience with heavy-duty vehicles has shown that a 4:1 to 20:1filtering technique, preferably about a 7:1 filtering technique,provides suitable responsiveness while filtering out the drivetrainnoises due to vibrations, torsionals and the like.

The present invention provides a control method/system for controllingan at least partially automated vehicular mechanical transmission systemwherein accessory torque and engine deceleration rate may be determinedwith the vehicle in motion or at rest.

When the vehicle is stopped with the engine idling and the transmissionin neutral or the master clutch disengaged, accessory torque (T_(ACCES))is substantially equal to gross engine torque minus base engine frictiontorque (T_(EG) -T_(BEF)). T_(EG) -T_(BEF) is also referred to as "netengine torque." This value is preferably sensed from the databus ordatalink (DL) and preferably subject to a filtering averaging process.

The system controller is provided with information which relates enginedeceleration rate (dES/dt rate) to accessory torque (T_(ACCES)) in apredetermined, substantially linear manner wherein engine decelerationrate equals A+(B * accessory torque) where "A" and "B" arepredetermined, stored parameters. If dES/dt rate is in units ofRPM/second and T_(ACCES) is in units of pound-feet, then "A" will be inunits of RPM/second and "B" will be in units of RPM/second/foot-pounds.FIG. 7 is a graphical representation of this relationship.

Using the foregoing relationship and the current value of accessorytorque, an expected engine deceleration rate may be determined while thevehicle is at rest. The rate thus determined or derived is anapproximation for the system logic to utilize for vehicle start-up andis corrected and updated using filtered, actually sensed enginedeceleration values as soon as the vehicle gets moving and makingupshifts.

When the vehicle is moving and has performed upshifts, enginedeceleration rate (dES/dt rate) may be determined by observing actualengine deceleration when the transmission is in neutral and enginefueling is reduced to a minimal value and, preferably, calculating afiltered average of the observed values. See, for example,aforementioned co-pending U.S. patent application Ser. No. 08/225,271,entitled ENGINE DECELERATION DETERMINATION METHOD/SYSTEM. Accessorytorque (T_(ACCES)) is then determined from the same predetermined linearrelationship discussed above, i.e., T_(ACCES) =(engine decelerationrate-A)÷B. Using the example of FIG. 7, engine deceleration rate equals-385+(-2 * T_(ACCEL)) and, at an observed, averaged engine decelerationrate (dES/dt rate) of -500 RPM/second, accessory torque (T_(ACCES))would equal about 81.25 pound feet.

While the linear relationship is defined as predetermined for a givenvehicle configuration, the relationship also may be adaptively learnedby the controller logic or empirically determined at the end of thevehicle assembly line. For example, to determine this substantiallylinear relationship during the end of the vehicle assembly line checkoutand testing procedure, the following procedure may be followed:

(1) Warm up vehicle engine to nominal operating temperature;

(2) Turn off all accessories (lights, air-conditioning, etc.) withvehicle stopped in neutral, then accelerate engine to governed speed bydepressing accelerator pedal, and then release pedal and monitor andrecord engine deceleration rate through a maximum operating speed (i.e.,about 1,800 RPM);

(3) Let engine idle and observe accessory torque by monitoring enginedatalink, this is one point on the line in FIG. 7;

(4) Turn on all accessories with vehicle stopped in neutral, thenaccelerate engine to governed speed by depressing accelerator pedal, andthen release pedal and monitor and record engine deceleration rate;

(5) Let engine idle and observe accessory torque by monitoring thedatalink, this is a second point on the line in FIG. 7; and

(6) Using the two points thus determined, determine the linear equationand enter the corresponding calibrations into the transmission systemcontroller.

It is noted that the foregoing procedure may be performed manually or asa routine in an end-of-line calibration computer logic. Alternatively, asimilar procedure may be incorporated into the transmission controllerlogic.

Utilizing the foregoing techniques, an accurate value of T_(FW) =T_(EG)-T_(BEF) -T_(ACCES) -T_(ACCEL) may be determined. The flywheel torque(T_(FW)) determination method/system of the present invention isschematically illustrated, in flow chart format, in FIGS. 4A and 4B.

Accordingly, it may be seen that a relatively simple and inexpensiveshift implementation control system/method for automated mechanicaltransmission system 10 is provided, which utilizes existing inputsignals and a determined relationship between unaided enginedeceleration rate (dES/dt rate) and accessory torque (T_(ACCES)) toprovide an accurate value indicative of the flywheel torque (T_(FW))control parameter.

Although the present invention has been described with a certain degreeof particularity, it is understood that various changes to form anddetail may be made without departing from the spirit and the scope ofthe invention as hereinafter claimed.

I claim:
 1. A method for controlling a vehicular automated systemincluding determining a value of a control parameter (T_(FW)) indicativeof engine flywheel torque of a vehicular internal combustion engine (E)in a vehicular automated mechanical tranmission system comprising a fuelthrottle-controlled internal combustion engine (E), a multiple-speedchange-gear mechanical transmission (10) having an input shaft (16) andan output shaft (90) adapted to drive vehicular drivewheels, said inputshaft drivingly connected to said engine by a master friction clutch (C)and a control unit (106) for receiving input signals, including an inputsignal (ES, IS) indicative of input shaft or engine rotational speed,and for processing said signals in accordance with predetermined logicrules to determine control parameters and to issue command outputsignals to transmission system actuators, including means forcontrolling fueling of the engine and means (70) for controllingshifting of the transmission, said method characterized by:determining arelationship ((dES/dt rate)=A+(B * T_(ACCES))) between enginedeceleration rate (dES/dt rate) and accessory torque (T_(ACCES));determining a value of a control parameter (dES/dt rate) indicative ofengine deceleration rate; determining a value of a control parameter(T_(ACCES)) indicative of accessory torque as a function of saidrelationship between accessory torque and engine deceleration rate andsaid value of a control parameter indicative of engine decelerationrate; determining a value of said control parameter indicative offlywheel torque (T_(FW)) as a function of the value of said controlparameter indicative of accessory torque (T_(ACCES)); and controllingsaid vehicular automated system as a function of the value of saidcontrol parameter indicative of flywheel torque.
 2. The control methodof claim 1 wherein said engine and said control unit communicate over anelectronic datalink (DL) carrying signals indicative of gross enginetorque (T_(EG)) and base engine friction torque (T_(BEF)) and saidcontrol parameter indicative of flywheel torque (T_(FW)) is determinedas a function of accessory torque (T_(ACCES)), gross engine torque(T_(EG)) and base engine friction torque (T_(BEF)).
 3. The controlmethod of claim 2 wherein said datalink operates in substantialconformance with one of SAE J1922 or J1939 protocols.
 4. The method ofclaim 1 wherein said relationship is predetermined and stored by saidcontrol unit.
 5. The method of claim 2 wherein said relationship issubstantially linear.
 6. The method of claim 1 wherein said inputsignals include an input signal (GR) indicative of currently engagedtransmission gear ratio, and further characterized by:determining avalue of a control parameter (T_(DW)) indicative of drivewheel torque asa function of said values of control parameters indicative of flywheeltorque (T_(FW)) and of engaged transmission gear ratio (GR); andcontrolling said vehicular automated system comprises controllingshifting of the transmission as a function of the value of said controlparameter indicative of drivewheel torque (T_(DW)).
 7. The controlmethod of claim 1 wherein said transmission system performs dynamicupshifts from an engaged ratio into a target gear ratio in a sequence ofoperations, all without disengagement of the master clutch andregardless of operator's setting of the throttle device, comprising:(a)a predip operation wherein fueling of the engine is manipulated to allowdisengagement of the engaged gear ratio; (b) after confirmation ofdisengagement of the engaged gear ratio, a synchronizing operationwherein fueling of the engine is reduced, allowing engine rotationalspeed to decrease toward the synchronous speed for engagement of thetarget ratio (ES=IS=OS * GR_(T)); and (c) after achieving substantialsynchronous rotational speed of said engine and causing engagement ofsaid target gear ratio, a throttle recovery operation wherein fueling ofthe engine is caused to be controlled by sensed operator setting of saidthrottle device; said determination of the value of a control parameter(dES/dt rate) indicative of engine deceleration rate comprising:duringthe predip operation, sensing engine speed; sensing initiation of saidsynchronizing operation, and upon sensing initiation of saidsynchronizing operation, causing sensed engine speed to equal enginespeed initial (RPM_(A)), and starting a timing sequence; sensinginitiation of the throttle recovery operation, and upon sensinginitiation of said throttle recovery operation, causing engine speed toequal engine speeed final (RPM_(B)), sensing elapsed time from startingof said timing sequence; and determining the current value of thecontrol parameter indicative of engine deceleration rate as a functionof the difference between engine speed final and engine speed initialand of the elapsed time.
 8. A method for determining a value of acontrol parameter (T_(FW)) indicative of the engine flywheel torque of avehicular internal combustion engine (E) in a vehicular automatedmechanical tranmission system comprising a fuel throttle-controlledinternal combustion engine (E), a multiple-speed change-gear mechanicaltransmission (10) having an input shaft (16) and an output shaft (90)adapted to drive vehicular drivewheels, said input shaft drivinglyconnected to said engine by a master friction clutch (C) and a controlunit (106) for receiving input signals, including an input signal (ES,IS) indicative of input shaft or engine rotational speed, an inputsignal (T_(GE)) indicative of gross engine torque and an input signal(T_(BEF)) indicative of base engine friction torque, and for processingsaid signals in accordance with predetermined logic rules to determinecontrol parameters and to issue command output signals to transmissionsystem actuators, including means for controlling fueling of the engineand means (70) for controlling shifting of the transmission, said methodcharacterized by:determining a value of control parameter (I) indicativeof engine moment of inertia; determining a relationship ((dES/dtrate)=A+(B * T_(ACCES))) between engine deceleration rate (dES/dt rate)and accessory torque (T_(ACCES)); determining a value of a controlparameter (T_(ACCEL)) indicative of acceleration torque as a function ofthe product of engine moment of inertia multiplied by current enginedeceleration (dES/dt * I); determining a value of a control parameter(dES/dt rate) indicative of engine deceleration rate; determining avalue of said control parameter (T_(ACCES)) indicative of accessorytorque as a function of said relationship and the value of saidparameter indicative of engine deceleration rate; determining a value ofsaid control parameter indicative of flywheel torque (T_(FW)) as afunction of the expression:

    T.sub.FW =T.sub.EG -T.sub.BEF -T.sub.ACCES -T.sub.ACCES

and controlling said transmission system as a function of the value ofsaid control parameter indicative of flywheel torque.
 9. The method ofclaim 8 wherein said values of at least some of said control parametersare determined as a filtered average value.
 10. The control method ofclaim 8 wherein said engine and said control unit communicate over anelectronic datalink (DL) carrying said signals indicative of grossengine torque (T_(EG)) and base engine friction torque (T_(BEF)). 11.The control method of claim 10 wherein said datalink operates insubstantial conformance with one of SAE J1922 or J1939 protocols. 12.The method of claim 8 wherein said value indicative of engine moment ofinertia (I) is a predetermined value stored by said control unit. 13.The method of claim 11 wherein said value indicative of engine moment ofinertia (I) is a predetermined value stored by said control unit. 14.The method of claim 8 wherein said relationship is predetermined andstored by said control unit.
 15. The method of claim 11 wherein saidrelationship is predetermined and stored by said control unit.
 16. Themethod of claim 13 wherein said relationship is predetermined and storedby said control unit.
 17. The method of claim 10 wherein saidrelationship is substantially linear.
 18. The method of claim 8 whereinsaid input signals include an input signal (GR) indicative of currentlyengaged transmission gear ratio, and further characterizedby:determining a value of a control parameter (T_(DW)) indicative ofdrivewheel torque as a function of said values of control parametersindicative of flywheel torque (T_(FW)) and of engaged transmission gearratio (GR); and controlling shifting of the transmission as a functionof the value of said control parameter indicative of drivewheel torque(T_(DW)).
 19. The control method of claim 8 wherein said transmissionsystem performs dynamic upshifts from an engaged ratio into a targetgear ratio in a sequence of operations, all without disengagement of themaster clutch and regardless of operator's setting of the throttledevice, comprising:(a) a predip operation wherein fueling of the engineis manipulated to allow disengagement of the engaged gear ratio; (b)after confirmation of disengagement of the engaged gear ratio, asynchronizing operation wherein fueling of the engine is reduced,allowing engine rotational speed to decrease toward the synchronousspeed for engagement of the target ratio (ES=IS=OS * GR_(T)); and (c)after achieving substantial synchronous rotational speed of said engineand causing engagement of said target gear ratio, a throttle recoveryoperation wherein fueling of the engine is caused to be controlled bysensed operator setting of said throttle device; said determination ofthe value of a control parameter (dES/dt rate) indicative of enginedeceleration rate comprising:during the predip operation, sensing enginespeed; sensing initiation of said synchronizing operation, and uponsensing initiation of said synchronizing operation, causing sensedengine speed to equal engine speed initial (RPM_(A)), and starting atiming sequence; sensing initiation of the throttle recovery operation,and upon sensing initiation of said throttle recovery operation, causingengine speed to equal engine speeed final (RPM_(B)), sensing elapsedtime from starting of said timing sequence; and determining the currentvalue of the control parameter indicative of engine deceleration rate asa function of the difference between engine speed final and engine speedinitial and of the elapsed time.
 20. The method of claim 8 furthercomprising evaluating feasibility of subsequent upshifts as a functionof the value of said control parameter indicative of flywheel torque(T_(FW)).
 21. The method of claim 19 further comprising evaluatingfeasibility of subsequent upshifts as a function of the value of saidcontrol parameter indicative of flywheel torque (T_(FW)).
 22. Thecontrol method of claim 18 wherein said transmission system performsdynamic upshifts from an engaged ratio into a target gear ratio in asequence of operations, all without disengagement of the master clutchand regardless of operator's setting of the throttle device,comprising:(a) a predip operation wherein fueling of the engine ismanipulated to allow disengagement of the engaged gear ratio; (b) afterconfirmation of disengagement of the engaged gear ratio, a synchronizingoperation wherein fueling of the engine is reduced, allowing enginerotational speed to decrease toward the synchronous speed for engagementof the target ratio (ES=IS=OS * GR_(T)); and (c) after achievingsubstantial synchronous rotational speed of said engine and causingengagement of said target gear ratio, a throttle recovery operationwherein fueling of the engine is caused to be controlled by sensedoperator setting of said throttle device; said determination of thevalue of a control parameter (dES/dt rate) indicative of enginedeceleration rate comprising:during the predip operation, sensing enginespeed; sensing initiation of said synchronizing operation, and uponsensing initiation of said synchronizing operation, causing sensedengine speed to equal engine speed initial (RPM_(A)), and starting atiming sequence; sensing initiation of the throttle recovery operation,and upon sensing initiation of said throttle recovery operation, causingengine speed to equal engine speeed final (RPM_(B)), sensing elapsedtime from starting of said timing sequence; and determining the currentvalue of the control parameter indicative of engine deceleration rate asa function of the difference between engine speed final and engine speedinitial and of the elapsed time.
 23. A control system for determining avalue of a control parameter (T_(FW)) indicative of the engine flywheeltorque of a vehicular internal combustion engine (E) in a vehicularautomated mechanical tranmission system comprising a fuelthrottle-controlled internal combustion engine (E), a multiple-speedchange-gear mechanical transmission (10) having an input shaft (16) andan output shaft (90) adapted to drive vehicular drivewheels, said inputshaft drivingly connected to said engine by a master friction clutch (C)and a control unit (106) for receiving input signals, including an inputsignal (ES, IS) indicative of input shaft or engine rotational speed,and for processing said signals in accordance with predetermined logicrules to determine control parameters and to issue command outputsignals to transmission system actuators, including means forcontrolling fueling of the engine and means (70) for controllingshifting of the transmission, said system characterized by:means fordetermining a relationship ((dES/dt rate)=A+(B * T_(ACCES))) betweenengine deceleration rate (dES/dt rate) and accessory torque (T_(ACCES));means for determining a value of a control parameter (dES/dt rate)indicative of engine deceleration rate; means for determining a value ofa control parameter (T_(ACCES)) indicative of accessory torque as afunction of said relationship and the value of said control parameterindicative of engine deceleration rate; means for determining a value ofsaid control parameter indicative of flywheel torque (T_(FW)) as afunction of the value of said control parameter indicative of accessorytorque (T_(ACCES)); and means for controlling said transmission systemas a function of the value of said control parameter indicative offlywheel torque (T_(FW)).
 24. The control system of claim 23 whereinsaid engine and said control unit communicate over an electronicdatalink (DL) carrying signals indicative of gross engine torque(T_(EG)) and base engine friction torque (T_(BEF)) and said controlparameter indicative of flywheel torque (T_(FW)) is determined as afunction of accessory torque (T_(ACCES)), gross engine torque (T_(EG))and base engine friction torque (T_(BEF)).
 25. The control system ofclaim 24 wherein said datalink operates in substantial conformance withone of SAE J1922 or J1939 protocols.
 26. The control system of claim 23wherein said relationship is predetermined and stored by said controlunit.
 27. The control system of claim 23 wherein said relationship issubstantially linear.
 28. The control system of claim 23 wherein saidinput signals include an input signal (GR) indicative of currentlyengaged transmission gear ratio, and further characterized by:means fordetermining a value of a control parameter (T_(DW)) indicative ofdrivewheel torque as a function of said values of control parametersindicative of flywheel torque (T_(FW)) and of engaged transmission gearratio (GR), and wherein said means for controlling said transmissionsystem controls said transmission system as a function of the value ofsaid control parameter indicative of drivewheel torque (T_(DW)).
 29. Thecontrol system of claim 23 wherein said transmission system performsdynamic upshifts from an engaged ratio into a target gear ratio in asequence of operations, all without disengagement of the master clutchand regardless of operator's setting of the throttle device,comprising:(a) a predip operation wherein fueling of the engine ismanipulated to allow disengagement of the engaged gear ratio; (b) afterconfirmation of disengagement of the engaged gear ratio, a synchronizingoperation wherein fueling of the engine is reduced, allowing enginerotational speed to decrease toward the synchronous speed for engagementof the target ratio (ES=IS=OS * GR_(T)); and (c) after achievingsubstantial synchronous rotational speed of said engine and causingengagement of said target gear ratio, a throttle recovery operationwherein fueling of the engine is caused to be controlled by sensedoperator setting of said throttle device; said means for determining thevalue of a control parameter (dES/dt rate) indicative of enginedeceleration rate comprising:means for, during the predip operation,sensing engine speed; means for sensing initiation of said synchronizingoperation, and upon sensing initiation of said synchronizing operation,causing sensed engine speed to equal engine speed initial (RPM_(A)), andstarting a timing sequence; means for sensing initiation of the throttlerecovery operation, and upon sensing initiation of said throttlerecovery operation, causing engine speed to equal engine speeed final(RPM_(B)), sensing elapsed time from starting of said timing sequence;and means for determining the current value of the control parameterindicative of engine deceleration rate as a function of the differencebetween engine speed final and engine speed initial and of the elapsedtime.
 30. A control system for determining a value of a controlparameter (T_(FW)) indicative of the engine flywheel torque of avehicular internal combustion engine (E) in a vehicular automatedmechanical tranmission system comprising a fuel throttle-controlledinternal combustion engine (E), a multiple-speed change-gear mechanicaltransmission (10) having an input shaft (16) and an output shaft (90)adapted to drive vehicular drivewheels, said input shaft drivinglyconnected to said engine by a master friction clutch (C) and a controlunit (106) for receiving input signals, including an input signal (ES,IS) indicative of input shaft or engine rotational speed, an inputsignal (T_(GE)) indicative of gross engine torque and an input signal(T_(BEF)) indicative of base engine friction torque, and for processingsaid signals in accordance with predetermined logic rules to determinecontrol parameters and to issue command output signals to transmissionsystem actuators, including means for controlling fueling of the engineand means (70) for controlling shifting of the transmission, saidcontrol system characterized by:means for determining a value of controlparameter (I) indicative of engine moment of inertia; means fordetermining a relationship ((dES/dt rate)=A+(B * T_(ACCES))) betweenengine deceleration rate (dES/dt rate) and accessory torque (T_(ACCES));means for determining a value of a control parameter (T_(ACCEL))indicative of acceleration torque as a function of the product of enginemoment of inertia multiplied by current engine deceleration (dES/dt *I); means for determining a value of a control parameter (dES/dt rate)indicative of engine deceleration rate; means for determining a value ofsaid control parameter (T_(ACCES)) indicative of accessory torque as afunction of said relationship and the value of said control parameterindicative of engine deceleration rate; means for determining a value ofsaid control parameter indicative of flywheel torque (T_(FW)) as afunction of the expression:

    T.sub.FW =T.sub.EG -T.sub.BEF -T.sub.ACCES -T.sub.ACCEL

and means for controlling operation of said transmission system as afunction of the value of said control parameter indicative of flywheeltorque (T_(FW)).
 31. The control system of claim 30 wherein said engineand said control unit communicate over an electronic datalink (DL)carrying said signals indicative of gross engine torque (T_(EG)) andbase engine friction torque (T_(BEF)).
 32. The control system of claim31 wherein said datalink operates in substantial conformance with one ofSAE J1922 or J1939 protocols.
 33. The control method of claim 5 whereinsaid relationship is determined according to the following procedure:(1)warming up the vehicle engine to nominal operating temperature; (2)turning off all accessories with vehicle stopped in neutral, thenaccelerate engine to governed speed by increasing fueling of engine, andthen defueling engine and monitoring and recording engine decelerationrate through a maximum operating speed; (3) then letting engine idle andobserving accessory torque by monitoring engine datalink to determineone point; (4) then turning on all accessories with vehicle stopped inneutral, then accelerate engine to governed speed by fueling the engine,and then defueling engine and monitoring and recording enginedeceleration rate; (5) then letting engine idle and observing accessorytorque by monitoring the datalink to determine a second point; and (6)then using the two points thus determined to determine the substantiallylinear relationship.
 34. The control method of claim 10 wherein saidrelationship is determined according to the following procedure:(1)warming up the vehicle engine to nominal operating temperature; (2)turning off all accessories with vehicle stopped in neutral, thenaccelerate engine to governed speed by increasing fueling of engine, andthen defueling engine and monitoring and recording engine decelerationrate through a maximum operating speed; (3) then letting engine idle andobserving accessory torque by monitoring engine datalink to determineone point; (4) then turning on all accessories with vehicle stopped inneutral, then accelerate engine to governed speed by fueling the engine,and then defueling engine and monitoring and recording enginedeceleration rate; (5) then letting engine idle and observing accessorytorque by monitoring the datalink to determine a second point; and (6)then using the two points thus determined to determine the substantiallylinear relationship.